Aeroclimatic requirements. For rainfed areas such as Iloilo, with Resource utilization. The development of LMVs would not require
a 5-6 month rice growing season, rice varieties with field duration of large changes in current cropping practices. Land use intensity would
about 90 days can be double cropped using wet seeded establishment increase somewhat as more upland second crops could be planted. Labor
techniques (Fig. 9). Both crops can be grown at least through the and capital use would remain virtually the same, with changes occurring
flowering stage during the period of the year that the probabilities of only In timing.
obtaining sufficient rainfall to support normal rice crop growth are
high. Contribution to household oblectlves. Due to improved yield
characteristics, a modest increase in rice production would be expected.
Scientists have already succeeded in breeding very early maturing Similarly, due to an early harvest, the potential for planting upland
varieties. In addition, rice varieties typically grown in temperate crops after rice would also increase (Figure 11). Assuming stable price
climates produce much more rapidly in the tropics, some in as little am levels, this would provide increased farm income as well as food for
70 days. However, experimental results at IRRI appear to demonstrate a home consumption. The timeliness of food provision would not vary
positive correlation between maturity and grain yield (Figure 10). The substantially from existing patterns.
earliest maturing variety currently being recommended for use in the
Philippines is IR28, which matures in 105 days. There is some question Institutional requirements. Adoption of an LMV would require no
as to the physical feasibility of producing new varieties with sig- new inputs or policies. Due to the similarity In timing to traditional
nificantly reduced field duration periods that still provide the high varieties, no special market requirements are foreseen.
yield potential of some of the later maturing varieties currently in
use. Significantly lower yield expectations could reduce the at- Manaxerial requirements. Management of LMVs would be similar to
tractiveness of very early maturing varieties vim a vim other currently that required of traditional varieties. The level of risk for the
available production technologies. second upland crop would, however, be reduced.
Accentabilitv to farmers. When questioned as to the potential Aroclimatie requirements. There is no reason to suspect that an
desirability of varieties with a very short field duration, all farmers LMV would not be biologically feasible, though most non-photoperiod
responded affirmatively. In fact, some of the farmers were already sensitive varieties are early maturing. In regards to suitabilitly to
experimenting with Japanese varieties that were said to mature in as rainfed climatic conditions, there should be no problem.
little as 70 days in the Philippines. Most farmers who tried these
varieties reported that yields were unacceptably low and that grain Acceptability to farmers. Due to the fact that LMV adoption would
quality was inferior. The Japanese varieties would have to be improved not stimulate great changes from current practices, farmers interviewed
upon in these two aspects before becoming acceptable to farmers, indicated that the technology would be acceptable. They were also able
to recognize the advantage in regards to an earlier establishment of the
Very early maturing varieties for the rainfed farming system appear upland crop.
promising providing problems of low yield and grain quality can be
overcome. The major positive factor would be the reduction of un- Notional Technology ? Photo-sensitive. early maturing varieties (PSys)
certainty in the system with respect to rice yields, as both crops could
'be fully grown under favorable conditions for rice. The development of early maturing, photoperiod sensitive rice
n Varieties could be used as a major component in a technology based upon National Technology 2 Late maturing varieties (LHVs) dry seeded rice. Previously, an analysis of DSR-based cropping patterns
revealed major problems with respect to maturity and weed growth that
If the positive relationship between rice yields and maturity would be alleviated or partially alleviated with the advent of such a
period is confirmed, it may be possible to increase output over current variety.
levels by growing a long duration, non-photoperiod sensitive high
yielding variety which can then be followed by an upland crop (Figure High photoperiod sensitivity is a desirable characteristic for a
9). The principal advantage of a non-photoperiod sensitive LMV over dry seeded rice variety, since maturity is principally determined by day
traditional varieties is that it could be harvested earlier in the length even though the planting date may vary. One of the major
season, leaving more time for establishing a subsequent upland crop problems with DSR is that of uneven maturity due to uneven germination
under favorable conditions. On fields in the higher landscape pa- and subsequent replanting of poor initial stands. Areas which require
sitions, where yield loss probabilities tend to be highest for a wet additional planting can be reseeded once rainfall has stabilized, and
seeded second rice crop planted late in the season, double rice cropping the new plants will mature at the same time as the older plants.
may not be viable in moat years. In such areas, the planting of a
late-maturing, high yielding single rice crop would be preferable over a
single short-duration rice crop. Ample time would remain for planting a
succeeding upland- crop.
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